Thrust bearing

ABSTRACT

A thrust bearing having a plurality of radially extending lubrication grooves formed on the bearing face thereof, and shallow, radially extending relief sections formed on the other face thereof, directly opposite and wider than the lubrication grooves.

[72] Inventor Warlmr %.llllemdlnm 5 Regemmm 3mm {21] A IND UNTTED STATESPATENTS m] 53 mm mm 2,306,048 12/1042 F1181 308/160 e d gu m Zeidler1004 878 4/1928 Flintermanm. 308/160 7 1 1 M w 1 w [3] figgfgf fifi1,494,010 5/1924 Newhouse 308/160 Primary Examiner-Martin P. SchwaclronAss/110mm Examiner-Frank Suslco Attorneys-E. W. Christen, A. M. Heiterand John P. Moran eew q 'llilIt US'li WEARING This invention relatesgenerally to thrust washers or bearings and more particularly to athrust bearing including novel means for preventing failure due to highunit loading on the raised radial edge portions resulting from thedisplacement of metal during formation of lubrication grooves on thebearing face thereof.

We have found that the formation of lubrication or other grooves on flatmetal surfaces by various forming methods, such as coining or stamping,displaces the metal involved and results in. metal protrusions beingformed adjacent the edges of the lubrication grooves. Unless theprotrusions are first ground off, once the thrust bearing is located inan assembly, such as adjacent the inner race of a clutch mechanism of anautomatic transmission, the life of the thrust bearing is reduced due tothe loading being carried by the raised metal portions, rather than bysubstantially the entire area of the bearing.

Accordingly, a primary object of this invention is to provide a thrustbearing, including novel means for preventing failure due to theabove-described condition.

Another object of the invention is to provide a thrust bearing whereinthe likelihood of failure as a result of high unit loading issubstantially lessened.

A more specific object of the invention is to provide a thrust bearingwherein a shallow recessed portion is formed opposite and wider thaneach groove, such as a lubrication groove, which is formed on thebearing face thereof, in order to allow a deflection under loadconditions of that portion of the bearing which contains raised metalprotrusions adjacent the grooves, the deflection being into the recessedareas.

These and other objects of the invention will become more apparent whenreference is made to the following specifica tion and accompanyingdrawings wherein:

FIG. 1 is a perspective view of a thrust bearing embodying theinvention;

FIG. 2 is a plan view of the thrust bearing illustrated in FIG.

FIG. 3 is a side elevational view taken along the plane of line 345 ofFIG. 2, and looking in the direction of the arrows, but with the thrustbearing positioned between a driving member and a nonrotating surface;

FIG. 41 is an enlarged cross-sectional view taken along the plane of theline M of FIG. 2, and looking in the direction of the arrows;

FIG. 5 is an enlarged cross-sectional view taken along the plane of theline 5-5 of FIG. 2, and looking in the direction of the arrows; and

FIG. 6 is a graphic representation of a characteristic of the invention.

Referring now to the drawings in greater detail, FIGS. 1, 2 and 3illustrate a typical thrust bearing 10 on which four (4) equally spacedtabs or tangs 12 are formed, pointing away from the bearing face Mthereof, to provide means for rotating the bearing 10 by an accompanyingrotating or driving member llt5, which may be a bearing race or otherassembly which subjects the bearing 10 to considerable load. The tangs12 extend into openings lid formed in the member 26. The bearing M,which may consist of any suitable material, such as a steel backing illwith a layer of bronze bonded thereto to form the bearing surface M, maybe plated with a layer of tinplate 20, if desired, for a lowercoefficient of friction.

Equally spaced lubrication grooves 22 (FIGS. 2 and 5) are formed on thebearing surface 14 prior to plating, by any suitable means, such asstamping or coining. The grooves 22 have very wide V-sections so theyterminate at their edges 26 in very small wedge angles for forcing oilbetween the bearing surfaces 20 and 28. The grooves 22 also taper from alarge section at the inner radius, permitting the entry of a largevolume of oil, to a smaller section at the outer radius to reduce theflow volume and pressurize the oil in the grooves due to the centrifugalforce effect. The stamping or other grooveforming process causes adisplacement of metal resulting in the formation of radially extendingraised portions 2% (FIG. d) adjacent the edges 26 of the grooves 22.

As a result of the raised portions 2d of displaced metal, it is apparentthat the overall flatness of the bearing surface M and/or the platedlayer 20 will be disrupted, and when the thrust bearing i0 is assembledwith its bearing surface M or 20 against a mating nonrotating member orsurface 2% (FIG. 3), there will result a condition wherein the entireload will be supported by the raised portions 2d adjacent the edges 26of the lubrication grooves 22, rather than having the load distributedover substantially the entire bearing surface M or 20, as it rotatesagainst the member 2d. Experience indicates that, prior to the formationof shallow, radially extending recesses 30 on the back side of thethrust bearing 10 directly opposite the grooves 22, and so long as theraised portions 2d have not been removed by a separate machiningoperation, the very high unit loading (curve A, FIG. 6) on the raisedportions 22 on each side of the grooves 22 prematurely wears through thelow coefficient of friction-plated material 20 thereon. This causes anincreased drag on the hearing it), increased heat, scoring and reducedlife of the bearing 10.

The recesses 30 are preferably formed in the same stamping or coiningoperation as the grooves 22. It has also been found that, when theserecesses 30 are provided on the side opposite the lubrication grooves22, the raised portions 241 may be reduced or eliminated by displacingthe metal into the recesses, but that it is difficult to maintain thedie condition which would completely eliminate the raised portions 24during a production run. This thrust washer construction providessignificantly improved and more consistent characteristics of operationand durability though raised portions 24 of varying degrees are presentat the edges 26 of the lubrication grooves 22. It is essential that therecesses 30 be circumferentially wider than the oppositely disposedlubrication grooves 22. The recesses 30 are shallow, say, 0.001 to 0.003inch deep, in order to not excessively weaken the bearing 10, butsufficient to provide controlled flexibility and to permit a smallcontrolled deflection of the bearing 10 in the vicinity of the grooves22 under load on the raised portions 24. This, of course, permits theentire surface 14, or, if plated, the surface 20, to come into contactwith and rotate against the surface of the adjacent stationary member2%. The use of the recesses 30 permits the naturally formed raisedportions 24L to remain, permitting an initial out-of-flatness conditionwhich becomes unimportant after assembly due to the: now inherentdeflection characteristic. If desired, the recesses 30 may be formed inthe adjacent surface of the member 16, which rotates with the bearing,and the thrust washer can have a thickness providing controlleddeflection at the lubrication grooves 22 opposite the unsupportedportion over the recesses 30.

It is believed that thrust washers with wide V-section lubricationgrooves still wipe too much oil from the facing bearing surface, andwhen there are raised portions at the edges of the grooves, thisundesirable condition is greatly increased; and furthermore, there is alocalized high unit load at the edges of each groove relative to thenormal load on the remainder of the bearing surface, as generallyindicated by curve A in FIG. 6. The improved and more consistentcharacteristics of opera tion and durability of thrust washers madeaccording to this invention significantly reduce the unit load at theedges of the grooves, particularly when there are raised portions at theedges of the grooves, and this increases the flow of lubricant from thegrooves for distribution circumferentially between the bearing surfaces.The degree of flexibility over the recesses controls and limits the unitload at the edges of the lubrication grooves to a predetermined valueand preferably provides a unit load at the edges of the lubricationgrooves of a reduced value which is substantially equal to, or lessthan, a normal operating unit load on the remainder of the bearingsurface M or 20. This construction prevents high localized unit loads atand adjacent the edges of the lubrication grooves which result in thewiping of the lubricant from the bearing surface and localizedoverheating. The substantially equal unit load arrangement with a thrustbearing having raised portions at the edges of the lubrication groovesis theoretically illustrated in curve B, FIG. 6, and provides veryuniform wear over the entire bearing surface for increased capacity.Further reduction of the unit load at the edges of the lubricationgrooves to a value less than the unit load on the remainder of thebearing surface will further increase the flow of lubricant between thebearing surfaces for increased cooling and load carrying capacity of theremainder of the bearing providing an overall increase in capacity.

It should be apparent that the thrust bearing described above embodies anovel feature which pen'nits lubrication grooves to be formed thereonwithout producing a localized increased load condition, but whichprovides improved lubrication and improved distribution of the unit loadfor greatly increased bearing life.

It should be further apparent that the invention embodies a featurewhich is simple and inexpensive to manufacture and yet highly efficientin operation.

While but one embodiment and application of the invention has been shownand described, it should be apparent that other modifications andapplications thereof are possible.

I claim:

1. In an assembly of the type described, a pair of operating membershaving facing planar member surfaces, means mounting said members forrelative movement longitudinally of said planar surfaces and forapplying a thrust load to one member to urge it in a directiontransverse to said planar surfaces toward the other member, a thrustbearing member positioned between said planar member surfaces and havingopposite planar bearing surfaces, one bearing surfaces being in contactwith one member surface and the other opposite bearing surface being incontact with the other member surface, at least one lubrication grooveformed in said thrust bearing member at one bearing surface with smallraised portions on said one bearing surface immediately adjacent saidgroove resulting from the displacement of material during the formationof said groove, recess means formed in said other surface of said thrustbearing means fixed at the region about said groove during operation toprovide room for displacement of said thrust bearing member in saidregion under load, and said thrust bearing member having sufficientflexibility in the region at said groove and raised portion to pennitdeflection of said region of said thrust bearing member so said raisedportion is deflected into the plane of said one bearing surface undernormal operating load to reduce the unit load on said raised portions,said thrust bearing remaining within the bounds of said facing planarmember surfaces.

2. An assembly of the type described comprising a pair of relativelyrotating members having substantially flat oppositely disposed faces, athrust bearing confined between said members, means nonrotatablyconnecting said thrust bearing to one of said members for causing saidthrust bearing to rotate relative to the other of said members, abearing surface formed on said thrust bearing for rotational slidingengagement with said other member, at lest one lubrication groove formedon said bearing surface with raised portions along the edges of saidgroove resulting from the transfer of metal during the formation of saidgroove, and recess means formed on said thrust bearing oppositelydisposed from said lubrication groove for permitting deflection of saidthrust bearing within the bounds of said substantially flat oppositelydisposed faces,

and said thrust bearing having flexibility for deflection under load onthe raised portions of said thrust bearing adjacent both edges of saidgroove to substantially reduce the unit load on said raised portions toa value compatible with the unit load on the remainder of said bearingsurface.

3. The invention defined in claim 2, and said unit load on said raisedportions being limited to a predetermined value.

4. The invention described in claim 2, and said unit load being equal toor less than the unit load on the remainder of said bearing surfaceunder normal operatin conditions.

5. The invention described in claim 4, w erem said lubrication groove isa wide V-groove extending radially across said bearing surface and saidrecess means being a radial recess wider than said groove and on thethrust bearing opposite said groove.

6. The thrust bearing described in claim 3, and said thrust bearinghaving sufficient flexiblity in said region so the unit load at saidedges is less than the unit load on the remainder of said bearingsurface.

7. A thrust bearing comprising a metal disc, a bearing surface formed onone face of said metal disc, a plurality of radially extendinglubrication grooves formed on said bearing surface, a raised portion ofdisplaced metal formed adjacent each edge of each lubrication groove,and a radially extending recessed portion formed on the other face ofsaid metal disc directly opposite each of said lubrication grooves andeach adjacent pair of said raised portions for permitting deflection ofsaid raised portions toward said recessed portions to reduce the load onsaid raised portions when said bearing surface is subjected to normalload conditions, the depth of said recessed portion being greater thanthe height of said raised portion and the width of said recessed portionbeing sufficient to permit the deflected portions to enter and remainwithin the planes of said faces of said metal disc.

8. The thrust bearing described in claim 7, and said unit load on saidraised portions being limited to a predetermined value.

9. A bearing assembly comprising a first member and a second membermounted for relative rotation and each member having a substantiallyflat face facing the other member, a thrust bearing between saidsubstantially flat faces of said members, means nonrotatably connectingsaid thrust bearing to said first member for causing said thrust bearingto rotate relative to said second member, said thrust bearing having abearing surface in rotational sliding engagement with said face of saidsecond member and an opposite surface in nonrotational engagement withsaid face of said first member, at least one lubrication groove formedradially across said bearing surface, and recess means formed on saidthrust bearing oppositely disposed from said lubrication groove forpermitting deflection under load of said thrust bearing in the region ofand adjacent both edges of said groove, said thrust bearing in theregion of said groove being flexible under normal operating loads fordeflection into said recess means intermediate said substantially flatfaces to substantially reduce the unit load at said edges of saidgroove, said lubrication groove being a wide V-groove extending radiallyacross said bearing surface tapering from a larger opensection at theinner radius of said thrust bearing to a smaller open section attheouter radius of said thrust bearing for permitting the entry of alarge volume of lubricating fluid at said inner radius and reducing theflow volume and pressurizing said fluid en route to said outer radiusdue to the action of centrifugal force.

1. In an assembly of the type described, a pair of operating membershaving facing planar member surfaces, means mounting said members forrelative movement longitudinally of said planar surfaces and forapplying a thrust load to one member to urge it in a directiontransverse to said planar surfaces toward the other member, a thrustbearing member positioned between said planar member surfaces and havingopposite planar bearing surfaces, one bearing surfaces being in contactwith one member surface and the other opposite bearing surface being incontact with the other member surface, at least one lubrication grooveformed in said thrust bearing member at one bearing surface with smallraised portions on said one bearing surface immediately adjacent saidgroove resulting from the displacement of material during the formationof said groove, recess means formed in said other surface of said thrustbearing means fixed at the region about said groove during operation toprovide room for displacement of said thrust bearing member in saidregion under load, and said thrust bearing member having sufficientflexibility in the region at said groove and raised portion to permitdeflection of said region of said thrust bearing member so said raisedportion is deflected into the plane of said one bearing surface undernormal operating load to reduce the unit load on said raised portions,said thrust bearing remaining within the bounds of said facing planarmember surfaces.
 2. An assembly of the type described comprising a pairof relatively rotating membErs having substantially flat oppositelydisposed faces, a thrust bearing confined between said members, meansnonrotatably connecting said thrust bearing to one of said members forcausing said thrust bearing to rotate relative to the other of saidmembers, a bearing surface formed on said thrust bearing for rotationalsliding engagement with said other member, at lest one lubricationgroove formed on said bearing surface with raised portions along theedges of said groove resulting from the transfer of metal during theformation of said groove, and recess means formed on said thrust bearingoppositely disposed from said lubrication groove for permittingdeflection of said thrust bearing within the bounds of saidsubstantially flat oppositely disposed faces, and said thrust bearinghaving flexibility for deflection under load on the raised portions ofsaid thrust bearing adjacent both edges of said groove to substantiallyreduce the unit load on said raised portions to a value compatible withthe unit load on the remainder of said bearing surface.
 3. The inventiondefined in claim 2, and said unit load on said raised portions beinglimited to a predetermined value.
 4. The invention described in claim 2,and said unit load being equal to or less than the unit load on theremainder of said bearing surface under normal operating conditions. 5.The invention described in claim 4, wherein said lubrication groove is awide V-groove extending radially across said bearing surface and saidrecess means being a radial recess wider than said groove and on thethrust bearing opposite said groove.
 6. The thrust bearing described inclaim 3, and said thrust bearing having sufficient flexiblity in saidregion so the unit load at said edges is less than the unit load on theremainder of said bearing surface.
 7. A thrust bearing comprising ametal disc, a bearing surface formed on one face of said metal disc, aplurality of radially extending lubrication grooves formed on saidbearing surface, a raised portion of displaced metal formed adjacenteach edge of each lubrication groove, and a radially extending recessedportion formed on the other face of said metal disc directly oppositeeach of said lubrication grooves and each adjacent pair of said raisedportions for permitting deflection of said raised portions toward saidrecessed portions to reduce the load on said raised portions when saidbearing surface is subjected to normal load conditions, the depth ofsaid recessed portion being greater than the height of said raisedportion and the width of said recessed portion being sufficient topermit the deflected portions to enter and remain within the planes ofsaid faces of said metal disc.
 8. The thrust bearing described in claim7, and said unit load on said raised portions being limited to apredetermined value.
 9. A bearing assembly comprising a first member anda second member mounted for relative rotation and each member having asubstantially flat face facing the other member, a thrust bearingbetween said substantially flat faces of said members, meansnonrotatably connecting said thrust bearing to said first member forcausing said thrust bearing to rotate relative to said second member,said thrust bearing having a bearing surface in rotational slidingengagement with said face of said second member and an opposite surfacein nonrotational engagement with said face of said first member, atleast one lubrication groove formed radially across said bearingsurface, and recess means formed on said thrust bearing oppositelydisposed from said lubrication groove for permitting deflection underload of said thrust bearing in the region of and adjacent both edges ofsaid groove, said thrust bearing in the region of said groove beingflexible under normal operating loads for deflection into said recessmeans intermediate said substantially flat faces to substantially reducethe unit load at said edges of said groove, said lubrication groovebeing a wide V-groOve extending radially across said bearing surfacetapering from a larger open section at the inner radius of said thrustbearing to a smaller open section at the outer radius of said thrustbearing for permitting the entry of a large volume of lubricating fluidat said inner radius and reducing the flow volume and pressurizing saidfluid en route to said outer radius due to the action of centrifugalforce.